The short answer
Not at all. Walking away is a recognised, expected move in the medina, as long as you do it calmly and politely. A vendor who lets you go without a new number has probably shown you their lowest price; one who calls you back still has room. Say 'la, shukran' with a smile and move on.
In more detail
What is rude is agreeing a price and then refusing to pay it. Before you name a figure, be sure you would be happy to buy at that price, because a stated offer that is accepted is treated as a deal.
Keep it good-natured. Bargaining in Marrakech is a social exchange, often over mint tea, and getting heated spoils it for both sides. Accepting tea does not commit you to buy.
If you would rather not bargain at all, shop at co-operatives and state-backed craft shops, where marked prices are fixed. The food stalls and the greengrocers in the Mellah are broadly fixed too.
Take your time before you start. Look at the same item in a few shops so you have a feel for quality and asking prices, and only begin bargaining for something you actually want.
Good to know
- Only offer a price you are willing to pay.
- Walk away calmly, never with heat.
- Use fixed-price shops if you hate haggling.